For a common illumination apparatus currently used, for instance, an illumination apparatus having a tubular light engine of a conventional light source, the light engine has to be electrically connected to a power supply via a connector device and has the location and illumination direction fixed thereby. However, after the currently known connector device is connected to the light engine, an illumination direction of the light engine cannot be adjusted, that is, the connection between the light engine and the connector device is mechanically fixed and cannot be changed, and it cannot achieve for instance the rotation of the light engine relative to the connector device to change the illumination direction of the light engine.
Besides, according to the designs of the currently known connector devices of other types, only after removing the connector device from the light engine, i.e., separating the connector device from the light engine, could the user adjust the illumination direction of the light engine, moreover, after the adjustment, the user should re-connect the light engine with the connector device. The above design of the connector device is quite unfavorable to the flexible use of the illumination apparatus, and the user cannot flexibly and conveniently adjust the light engine to make the illumination of the illumination apparatus adapted to particular application circumstances, such design limits the situations where the illumination apparatus can be applied, and the user has to look for a lamp holder matching the light engine to ensure that the light can illuminate in a correct direction. Such illumination apparatus is not friendly to the user.